The Elements of Agriculture A Book for Young Farmers, with Questions Prepared for the Use of Schools, George E. Waring [read aloud books TXT] 📗

a mechanical manure. The compound of sand and potash,[U] as well as the potash alone, may enter into the composition of plants, and hence it is a chemical manure. In other words, potash belongs to both classes described above. SECTION 3 (MANURES) CHAPTER I (CHARACTER AND VARIETIES OF MANURES) Pg 82

 

It is important that this distinction should be well understood by the learner, as the words "mechanical" and "chemical" in connection with manures will be made use of throughout the following pages.

[What are absorbents?

What kind of manure is charcoal?]

There is another class of manures which we shall call absorbents. These comprise those substances which have the power of taking up fertilizing matters, and retaining them for the use of plants. For instance, charcoal is an absorbent. As was stated in the section on soils, this substance is a retainer of all fertilizing gases and many minerals. Other matters made use of in agriculture have the same effect. These absorbents will be spoken of more fully in their proper places.

TABLE.

MECHANICAL MANURES are those which improve the mechanical condition of soils.

CHEMICAL " are those which serve as food for plants.

ABSORBENTS are those substances which absorb and retain fertilizing matters.

 

SECTION 3 (MANURES) CHAPTER I (CHARACTER AND VARIETIES OF MANURES) Pg 83

[Into what classes may manures be divided?

What are organic manures?

Inorganic? Atmospheric?]

Manures may be divided into three classes, viz.: organic, inorganic, and atmospheric.

ORGANIC manures comprise all animal and vegetable matters which are used to fertilize the soil, such as dung, muck, etc.

INORGANIC manures are those which are of a purely mineral character, such as lime, ashes, etc.

ATMOSPHERIC manures consist of those organic manures which are in the form of gases in the atmosphere, and which are absorbed by rains and carried to the soil. These are of immense importance. The ammonia and carbonic acid in the air are atmospheric manures.

FOOTNOTES:

[U] Silicate of potash.

SECTION 3 (MANURES) CHAPTER II (EXCREMENTS OF ANIMALS) Pg 84

 

[Of what is animal excrement composed?

Explain the composition of the food of animals.

What does hay contain?

To what does Liebig compare the consumption of food by animals, and why?]

The first organic manure which we shall examine, is animal excrement.

This is composed of those matters which have been eaten by the animal as food, and have been thrown off as solid or liquid manure. In order that we may know of what they consist, we must refer to the composition of food and examine the process of digestion.

The food of animals, we have seen to consist of both organic and inorganic matter. The organic part may be divided into two classes, i. e., that portion which contains nitrogen--such as gluten, albumen, etc., and that which does not contain nitrogen--such as starch, sugar, oil, etc.

The inorganic part of food may also be divided into soluble matter and insoluble matter.

DIGESTION AND ITS PRODUCTS.

[Of what does that part of dung consist which resembles soot?

What else does the dung contain?

In what manner does the digested part of food escape from the body?]

Let us now suppose that we have a full-grown ox, which is not increasing in any of his parts, but only consumes food to keep up his respiration, and to supply the natural wastes of his body. 

SECTION 3 (MANURES) CHAPTER II (EXCREMENTS OF ANIMALS) Pg 85

 

To this ox we will feed a ton of hay which contains organic matter, with and without nitrogen, and soluble and insoluble inorganic substances. Now let us try to follow it through its changes in the animal, and observe its destination. Liebig compares the consumption of food by animals to the imperfect burning of wood in a stove, where a portion of the fuel is resolved into gases and ashes (that is, it is completely burned), and another portion, which is not thoroughly burned, passes off as soot. In the animal action in question, the food undergoes changes which are similar to this burning of wood. A part of the food is digested and taken up by the blood, while another portion remains undigested, and passes the bowels as solid dung--corresponding to soot. This part of the dung then, we see is merely so much of the food as passes through the system without being materially changed. Its nature is easily understood. It contains organic and inorganic matter in nearly the same condition as they existed in the hay. They have been rendered finer and softer, but their chemical character is not materially altered. The dung also contains small quantities of nitrogenous matter, which leaked out, as it were, from the stomach and intestines. The digested food, however, undergoes further changes which affect its character, and it escapes from the body in three ways--i. e., through the lungs, through the bladder, and through the bowels. It will be recollected from the first section of this book, p. 22, that the carbon in the blood of animals, unites with the oxygen of the air drawn into the lungs, and is thrown off in the breath as carbonic acid. The hydrogen and oxygen unite to form a part of the water which constitutes the moisture of the breath.

SECTION 3 (MANURES) CHAPTER II (EXCREMENTS OF ANIMALS) Pg 86

 

[Explain the escape of carbon, hydrogen and oxygen.

What becomes of the nitrogenous parts?

How is the soluble ash of the digested food parted with?

The insoluble?

If any portions of the food are not returned in the dung, how are they disposed of?]

That portion of the organic part of the hay which has been taken up by the blood of the ox, and which does not contain nitrogen (corresponding to the first class of proximates, as described in Sect. I), is emitted through the lungs. It consists, as will be recollected, of carbon, hydrogen and oxygen, and these assume, in respiration, the form of carbonic acid and water.

The organic matter of the digested hay, in the blood, which contains nitrogen (corresponding to the second class of proximates, described in Sect. I), goes to the bladder, where it assumes the form of urea--a constituent of urine or liquid manure.

We have now disposed of the imperfectly digested food (dung), and of the organic matter which was taken up by the blood. All that remains to be examined is the inorganic or mineral matter in the blood, which would have become ashes, if the hay had been burned. The soluble part of this inorganic matter passes into the bladder, and forms the inorganic part of urine. The insoluble part passes the bowels, in connection with the dung.

SECTION 3 (MANURES) CHAPTER II (EXCREMENTS OF ANIMALS) Pg 87

 

[How is their place supplied?

Is food put out of existence when it is fed to animals?

What does the solid dung contain? Liquid manure? The breath?]

If any of the food taken up by the blood is not returned as above stated, it goes to form fat, muscle, hair, bones, or some other part of the animal, and as he is not growing (not increasing in weight) an equivalent amount of the body of the animal goes to the manure to take the place of the part retained.[V]

We now have our subject in a form to be readily understood. We learn that when food is given to animals it is not put out of existence, but is merely changed in form; and that in the impurities of the breath, we have a large portion of those parts of the food which plants obtain from air and from water; while the solid and liquid excrements contain all that was taken by the plants from the soil and manures.

The